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Head-to-head evidence comparison — which supplement is right for you?
B-Complex wins 1 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Probably helps
5 of 8 studies with measurable effects showed benefit.
Top outcomes
Verdict
Probably helps
9 of 13 studies with measurable effects showed benefit.
Top outcomes
1 capsule daily (per label)
Morning with breakfast
Methylated B-complex (methylcobalamin, methylfolate)
18-45mg elemental iron for deficiency (varies by severity)
On empty stomach if tolerated, Away from tea, coffee, dairy
Ferrous bisglycinate (gentle, well-absorbed) or iron protein succinylate
2-4 weeks
4-8 weeks
Immediate
2-4 weeks
4-8 weeks
4-12 weeks
Dosage exploration of combined B-vitamin supplementation in stroke prevention: a meta-analysis and systematic review
The American journal of clinical nutrition (2024) · Meta analysis · n=76664
In areas without and with partial folic acid fortification, combined B-vitamin supplementation significantly reduced the risk of stroke by 34% [RR: 0.66; 95% confidence interval (CI): 0.50, 0.86] and 11% (RR: 0.89; 95% CI: 0.79, 1.00), respectively.
A Comparative Study Evaluating the Effectiveness of Folate-Based B Vitamin Intervention on Cognitive Function of Older Adults under Mandatory Folic Acid Fortification Policy: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Nutrients (2024) · Meta analysis · n=42768
The meta-analysis on the effects of folate-based B vitamin supplementation on cognitive function showed a significant overall impact (Z = 3.84; p = 0.0001; SMD, 0.18; 95% CI, 0.09, 0.28).
A Systematic Review and Meta-Analysis of B Vitamin Supplementation on Depressive Symptoms, Anxiety, and Stress: Effects on Healthy and 'At-Risk' Individuals
Nutrients (2019) · Meta analysis · n=2015
Regarding individual facets of mood, B vitamin supplementation benefited stress (n = 958, SMD = 0.23, 95% CI = 0.02, 0.45, p = 0.03).
Daily oral iron supplementation during pregnancy
The Cochrane database of systematic reviews (2024) · Meta analysis · n=48971
There is probably little to no difference in maternal death (2 versus 4 events, RR 0.57, 95% CI 0.12 to 2.69; 3 trials, 14,060 women; moderate-certainty evidence).
The Prevalence of Anemia among Pregnant Women in China: A Systematic Review and Meta-Analysis
Nutrients (2024) · Meta analysis · n=722
The results showed that the prevalence of anemia, ID, and IDA among pregnant women in China were 30.7% (95% CI: 26.6%, 34.7%), 45.6% (95% CI: 37.0%, 54.2%), and 17.3% (95% CI: 13.9%, 20.7%), respectively.
Treatment for women with postpartum iron deficiency anaemia
The Cochrane database of systematic reviews (2024) · Meta analysis · n=572
Intravenous iron versus oral iron supplementation The evidence is very uncertain about the effect of intravenous iron on mortality (risk ratio (RR) 2.95, 95% confidence interval (CI) 0.12 to 71.96; P = 0.51; I² = not applicable; 3 RCTs; 1 event; 572 women; very low-certainty evidence).
Multiple meta-analyses show small but statistically significant benefits for cognitive function in older adults and stroke prevention populations. Effect sizes are modest (SMD ~0.15-0.18). Benefits may be more pronounced in B-vitamin deficient populations.
Based on meta-analyses showing hemoglobin improvements of 2.01-5.30 g/dL in iron deficient populations. Higher doses show diminishing returns with increased GI side effects. Effectiveness varies significantly by baseline iron status and form used.
AI-estimated from published studies. Interpret as directional guidance.
B-Complex has a higher evidence score (9/10 vs 9/10) and wins in 1 of 3 categories.
For boost daily energy, Iron has a higher relevance score (90 vs 80).
No known interactions between B-Complex and Iron have been documented in our database. However, always consult a healthcare provider before combining supplements.